CN109219564B

CN109219564B - Ergonomically integrated handle assembly

Info

Publication number: CN109219564B
Application number: CN201780034392.5A
Authority: CN
Inventors: 尼克·梅林
Original assignee: Integrated Plastics Pty Ltd
Current assignee: Integrated Plastics Pty Ltd
Priority date: 2016-04-04
Filing date: 2017-04-04
Publication date: 2020-06-12
Anticipated expiration: 2037-04-04
Also published as: SA518400171B1; IL280156A; AU2017245933C1; US20200324937A1; NZ747182A; EP3439980A1; SG11201808658RA; KR102360282B9; IL275756B; JP2019513581A; WO2017173477A1; CN109219564A; IL262078A; ZA201806719B; IL275756A; EP3439980A4; US20230182958A1; KR102360282B1; KR102627036B1; IL262078B

Abstract

A method of handling a preform for stretch blow moulding a container having an integrally formed handle, the preform comprising a body portion and an integrally formed handle, the preform being transferred from a supply of preforms to a blow moulding mould for blow moulding the container, the method comprising the steps of: -passing the preform through a preform handle orientation device; -transferring the preforms to a preform transport system; -maintaining the preform handle orientation applied by the orientation device during transfer to the transfer system and the blow-moulding mould; -rotating the preforms along the transport system during transport past the array of preform heating elements while protecting the handle from overexposure to the heating elements; and-transferring the preforms from the conveying system to the blow-moulding mould, the handle comprising a loop of orientable material extending between upper and lower connecting zones of the body portion of the preform, characterized in that the gradually widening cross-section of the handle from near the lower connecting zone to near the upper connecting zone has a substantially uniform cross-section which reaches and maintains a maximum width near the upper connecting zone.

Description

Ergonomically integrated handle assembly

Technical Field

The present invention relates to containers blow molded from injection molded preforms, and more particularly to such containers provided with an integral handle.

Background

Blow molded containers having integral handles are well known and are variously disclosed in various patents and applications held by the applicant, including WO 2007101309.

These documents describe various manufacturing methods and features of the handles of these containers. However, it is apparent that there are some deficiencies in the initial formation of the handle profile and the configuration of the handle profile at the junction of the preform body and the resulting blow-molded container (particularly at the attachment near the neck of the container). In this area, particularly for larger capacity containers, uncomfortable pressure may be applied to the index finger when the container is lifted by hand.

Another disadvantage of the handle described in the above cited prior art is that: forming the handle requires a relatively wasteful volume of material. In addition, the reticulated "i-beam" structure of the handle is aesthetically undesirable.

It is an object of the present invention to address or at least ameliorate some of the above disadvantages.

Note

The term "comprising" (and grammatical variants thereof) is used in the specification in an open-ended sense of "having" or "including" and not in an exclusive sense of "consisting only of.

The above discussion of prior art in the context of the present invention is not an admission that any of the information discussed therein is part of the common general knowledge of a person skilled in the art in the applicable prior art or any country.

Disclosure of Invention

Accordingly, in a first broad form of the present invention, there is provided a method of controlling a preform for stretch blow moulding a container having an integrally formed handle; the preform comprises a body portion and the integrally formed handle; the preform is transferred from a preform supply to a blow-moulding mould for blow-moulding the container; the method comprises the following steps:

-passing the preform through preform handle orientation means;

-transferring the preforms to a preform transport system;

-maintaining the orientation of the preform handle applied by the preform handle orientation device during transfer to the preform transport system and to the blow moulding mould;

-rotating the preforms along the preform transport system past an array of preform heating elements during transport while protecting the integrally formed handles from overexposure to the heating elements; and

-transferring the preforms from the preform transport system to the blow moulding moulds,

wherein the handle comprises a loop of orientable material extending between upper and lower attachment areas located on the body portion of the preform; wherein the handle has a generally uniform cross-section from adjacent the lower attachment region to a progressively widening cross-section proximate the upper attachment region; the substantially uniform cross-section reaches and maintains a maximum width proximate the upper attachment area.

In another broad form of the invention, there is provided a method of controlling a preform for stretch blow moulding a container having an integrally formed handle, the preform comprising a body portion and the integrally formed handle, the preform being transferred from a supply of preforms to a blow moulding mould for blow moulding the container, the method comprising the steps of:

-transferring the preforms from the transport system to the blow-moulding moulds,

wherein the handle comprises a loop of orientable material extending between upper and lower attachment zones on the body portion of the preform, characterised in that the handle has a generally uniform cross-section from adjacent the lower attachment zone to a progressively widening cross-section proximate the upper attachment zone, the generally uniform cross-section reaching and maintaining a maximum width adjacent the upper attachment zone.

Preferably, the method further comprises the steps of:

-passing the preform through preform handle orientation means;

-transferring the preforms to a preform transport system;

-maintaining the orientation of the preform handle applied by the preform handle orientation device during transfer to the preform transport system and to the blow moulding mould.

Preferably, the method comprises the steps of:

-rotating the preforms along the preform transport system during transport past an array of preform heating elements while protecting the integrally formed handles from overexposure to the heating elements.

In another broad form of the invention, there is provided a handle for a stretch blow molded container; the container is blow moulded from a preform comprising the handle as an integral ring of orientable material extending from an upper to a lower attachment region; the handle includes a linear lower portion and an arcuate portion extending from one end of the linear lower portion to the upper connection region; the handle has a generally uniform cross-section from near the lower attachment region to a gradually widening cross-section proximate the upper attachment region, the generally uniform cross-section reaching and maintaining a maximum width near the upper attachment region.

Preferably, the cross-section of the handle extends from opposite outer edges towards a centre line; the cross-sectional thickness increases from the outer edge to a maximum thickness at the centerline.

Preferably, the handle includes a straight line portion inclined downward from the lower connection region and an arc portion extending from one end of the straight line portion to the upper connection region.

Preferably, a first reinforcing element, a second reinforcing element and a third reinforcing element are integrally formed at each of the upper connecting region and the lower connecting region and at a joint portion between the linear portion and the arc portion, respectively.

Preferably, said first reinforcing element at said upper attachment region comprises a first curved element having a width and cross-section substantially corresponding to the width and cross-section of said handle adjacent said upper attachment region; the first bending element extends from a first separate attachment area below the upper attachment area to merge with the handle near a first end of the handle having a maximum width.

Preferably, the second reinforcing element at the lower connection region comprises a straight line element having a width and cross-section substantially corresponding to the width and cross-section of the straight portion of the handle; the straight line element extends from a second separate connection region above the lower connection region to merge with the straight line portion of the handle near the lower connection region.

Preferably, the third reinforcing element at the junction of the linear portion and the arcuate portion of the handle comprises a further curved element having a width and cross-section substantially corresponding to the width and cross-section of the handle adjacent the junction of the linear portion and the arcuate portion of the handle; each outer end of the further curved element merges with the linear portion and the arcuate portion of the handle.

Preferably, each reinforcing element comprises a web portion of orientable material located within the limits formed respectively between the main portion and the first reinforcing element, between the main portion and the second reinforcing element and between the third reinforcing element and the linear portion and the arcuate portion of the preform, each web portion of orientable material being aligned with the centre line and extending equally in both directions from the centre line.

In another broad form of the invention, there is provided a method of reducing the pressure on a supporting finger lifting a blow molded container; the container is provided with an integrated handle; the method comprises the following steps:

-stretch blow moulding the container from a preform comprising an integral loop of orientable material forming the handle; a loop of the orientable material extending between an upper connection region and a lower connection region;

-forming the handle with an arc-shaped portion extending from a lower portion to the upper connecting region;

-widening the cross-sectional profile of the arc-shaped portion in the vicinity of the upper connection region to a maximum width of the handle;

-providing a reinforcement element in the vicinity of said upper connection zone; the reinforcing element includes a first curved element having a width and cross-section substantially corresponding to a width and cross-section of the handle proximate the upper attachment region, the first curved element extending from a first separate attachment region below the upper attachment region to merge with the handle proximate a first end of the maximum width of the handle.

Preferably, the curvature of the stiffening element is selected to fit the normal size index finger of a human hand.

In yet another broad form of the invention, there is provided a handle for a stretch blow molded container; the container is blow moulded from a preform comprising the handle as an integral ring of orientable material extending from an upper to a lower attachment region; the handle includes a linear lower portion and an arcuate portion extending from one end of the linear lower portion to the upper connection region; the handle has a generally uniform cross-section from near the lower attachment region to a gradually widening cross-section proximate the upper attachment region, the generally uniform cross-section reaching and maintaining a maximum width near the upper attachment region.

Drawings

Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

FIGS. 1, 1A and 1B are views of a container and preform according to the prior art;

FIG. 2 is a side view of a preferred embodiment of a preform and an integrally attached handle according to the present invention;

FIG. 3 is an end view of the preform and handle of FIG. 1;

FIG. 4 is a top view of the preform and handle of FIGS. 1 and 2;

fig. 5A to 5C show cross-sections of the handle of fig. 2 to 4 at various positions;

FIG. 6 is a side view of a container that may be stretch blow molded from the preform shown in FIGS. 2-4;

FIG. 7 is a top view of a possible stretch blow molding machine suitable for producing the container of FIG. 6 from the preform of FIGS. 2 and 3;

FIG. 8 is a side view of a preform being conveyed on the conveyor system of the machine of FIG. 7;

FIGS. 9 and 9A illustrate a method of feeding and orienting preforms with integral handles for use in the machine of FIG. 7;

FIG. 10 is a partial cross-sectional view of an integral handle of a preform nested in an insulation; and

fig. 11 is a view of a preform with an integral handle entering a stretch blow molding mold for blow molding a container such as that shown in fig. 1 and 6.

Detailed Description

In this specification, the term "integrally connected" or "integrally connected" means that the connection between the handle and the preform (and the corresponding connection on the container subsequently blow-moulded from the preform) is formed from the same material as the handle and preform and is formed as an intrinsic part at the same time as the preform is formed.

The preform and integrally attached handle of the present invention are used to produce a stretch blow molded container of oriented PET material, as shown in fig. 6, which includes an integral handle. There are generally two processes for stretch blow molding containers from polymeric materials: 1) a single stage process, wherein a preform is formed and the container is blow molded on the same machine; and 2) a two-stage process, forming a preform on one machine and then blow molding the container on another machine (possibly located at another remote location).

The single stage equipment is capable of processing PVC, PET and PP. Once the preform or parison is formed (extrusion or injection molding), it is passed through a conditioning station that brings it to the appropriate orientation temperature. The single stage system allows the process to process raw materials into finished products in one machine, but the process is best suited for dedicated applications and low throughput because it is not easy to change tools.

With the two-stage process, the processing parameters for preform manufacturing and container blow molding can be optimized. The processing machine does not have to compromise preform design and weight, productivity and container quality as on a single stage apparatus. The user can make or purchase the preform. If the user chooses to make a preform, he can make the preform in one or more places suitable for his market. Both high output machines and low output machines are possible. In the two-stage process, the preforms are introduced into the stretch blow molding machine at ambient temperature and special preheating devices are required before the preforms enter the blow molding molds.

In this specification, the term "integrally connected" or "integrally connected" means that the connection between the handle and the preform (and the corresponding connection on the container subsequently blow-moulded from the preform) is made of the same material as the handle and the body of the preform and is formed as an intrinsic part of the injection moulded preform.

Fig. 1 shows a container according to the prior art, which is stretch blow molded from a preform (fig. 1A) comprising an integral handle. As can be seen in the end view of fig. 1B, the handle forms a profile of constant width throughout the length between the upper and lower connection regions. While the "i-beam" form of the handle profile provides strength, the relatively narrow area adjacent the upper attachment area makes this form of handle uncomfortable, especially for large containers, such as 2 liter or larger, which can be held in the hand over extended periods of time and can even be painful.

Turning now to fig. 2, in a preferred form of the invention, preform 100 includes a neck 102, a body portion 103 and a handle 113. The neck 102 has a threaded portion 104 and a retaining ring 105. The preform is injection molded from a PET material. As can be seen in fig. 6, in the present invention, the configuration of the handle that is injection molded in the preform state remains unchanged through the stretch blow molding process that forms the container of fig. 6.

To produce the container shown in fig. 6, the preform 100 shown in fig. 2-4 is fed into a blow-molding machine (e.g., blow-molding machine 510, shown schematically in fig. 7) and blow-molded according to a biaxially oriented blow-molding technique, according to an embodiment of the present invention. In the process, as shown in fig. 8 and 10, the neck 102 is held in the mandrel 513 of the transfer system of the blow-molding machine 510 to prevent the neck 102 from expanding in the stretch blow-molding mold 517.

Initially, the expandable portion of the preform below the neck may be mechanically pulled down to the bottom of the mold, and then the body of the preform may be blown outward by applying compressed air as is well known in the art.

In one preferred form, referring to fig. 7, the stretch blow molding machine 510 includes a chain driven conveyor 516, the chain driven conveyor 516 having a plurality of spindles 513, the plurality of spindles 513 being mounted on the chain driven conveyor 516 at substantially equal intervals such that each spindle follows a substantially elliptical path through a plurality of processing stations on the blow molding machine 510.

Referring to fig. 7 and 8, preforms 100 mounted on mandrels 513 as shown in fig. 8 are advanced from a loading station 515 of a blow molding machine 510 to a stretch blow molding station 517 and thence to an unloading station 518 via a series of conditioning heaters 521. A separate drive system 522 ensures that the preform is rotated as it passes through the heater 521 to ensure uniform heating of the preform body.

As shown in fig. 8, each mandrel 513 includes insulation 519. Although this thermal insulation is used in a different configuration of the preform handle than the present invention, the process of installation into the mandrel provided with the thermal insulation, preheating of the preform and advancement in the stretch blow molding stage is in principle the same as the process to which the preform and handle of the present invention are applied.

The thermal insulation 519 is adapted to receive the integral handle 113 of the preform 100 internally so as to protect the handle 113 from heat applied by the radiant heater 521 as the preform is conveyed through the heating station in the direction indicated by the arrow in fig. 7.

It will be appreciated that the orientation of the handle must be controlled as the preform is inserted into the mandrel before it enters the heating stage so that the insulation 519 can be properly fitted on the handle 113.

Furthermore, it is important that each preform 100 is provided to the stretch blow moulding tool 517 with the handle and insulation correctly oriented so that when the blow moulding phase is finished as in fig. 11, the handle and insulation are correctly enclosed in the half mould.

Referring to fig. 9 and 9A, in one preferred arrangement, preforms 100 are fed to the feed rail 724 at the loading station 530 from a suitable supply (e.g., a hopper or vibratory bowl as shown in fig. 7). As shown in fig. 9, the feed rail 724 is arranged so that the preforms 100 are advanced along the rail 724 by gravity, vibration or other linear conveyance means, and the preforms 100 are supported between

parallel rail elements

725 and 726 on the underside of the positioning ring 105.

During transport along the feed rail 724, the orientation of the handles 113 of the preforms is preferably controlled by guide channels (not shown) to loosely constrain the handles to an orientation close to or at right angles to the direction of travel. Thus, with the handle 113 pointing generally forward of the body 103 or trailing the body 103, the preform 100 is constrained to advance along the feed rail 724. An escapement mechanism (not shown) at the end of the feed rail 724 is provided for controlling the sequential ejection of individual preforms 100 from the end of the rail.

The preforms thus released from feeder rail 724 are allowed to fall vertically into an orienting device 732 shown in fig. 9A, which orienting device 732 is fixed directly below the escapement mechanism at the end of feeder rail 724. In a preferred form, the orienting device 732 shown in FIG. 9A is comprised of a frustoconical sleeve 734, the inner diameter of the sleeve 734 being adapted to allow the cylindrical body 103 of the preform and the retaining ring 105 to slide freely therethrough. The wall of the sleeve 734 is provided with a slit 736 extending along the length of the sleeve, the slit 736 extending from a handle inlet opening 738 at an upper edge 749 of the sleeve 734 to a handle outlet opening 740 at a lower edge 741. The slit has a sufficient width to allow the handle 113 of the preform 100 to slide through.

The

upper edges

745 and 743 of the sleeve 734 are formed to guide the handle 113 into the slot 736. To this end, the

upper edges

745 and 743 are formed as handle inlet openings 738 that slope sharply downwardly from respective

high points

744 and 744A diametrically opposite the handle inlets to the slots 736. To ensure that the handle does not fall down and snap over the highest point on the

upper edges

743 and 745, the feeder rail 724 is disposed at a generally right angle to the radial position of the slot 736. Thus, the handle 113 is prevented from adopting this orientation as it advances along the feeder rail 724 as described above, such that the handle 113 does not contact the highest point of the

upper edges

743 and 745, but instead falls onto the orienting device with the handle contacting the sloped

upper edge

743 or 745.

The

beveled edges

743 and 745 slope downwardly from the

peaks

744 and 744A to each side of the slot 736, each side terminating in a respective smooth

rounded corner

748 and 749 at the handle entrance opening 738. The slope is sufficient to ensure that the handle 113 of the preform 100 slides along the sloped edge portion.

In the case where the handle 113 is not aligned with the slot 736, when the handle is in contact with the

beveled portions

743 or 745, the preform 100 dropped into the orientation apparatus 732 will rotate while sliding downward under its own weight until the handle 113 is aligned with the slot 736 and the preform 712 falls cleanly into the apparatus.

Directly below the device 732, there is arranged a rotary indexing table (not shown) having a plurality of equi-spaced nests arranged around its periphery, the nests being arranged such that at each index of the indexing table each successive nest reaches a position aligned with the axis of the device 732. The nest is adapted to receive the preform 100 and hold the preform 100 in the following manner: such that the orientation of handle 113 originally imparted by device 732 is maintained with respect to each nest during retention of the preforms in the nests.

When the preform 100 reaches the transfer station 515 (see fig. 7) by indexing of the indexing table, it is ejected upwards from the nest supporting it to engage one of the succession of spindles 513 of the preform transport system 516, so as to perform work between the loading station 515 and the blow moulding tool 517. A preferred mandrel configuration with a preform attached is shown in fig. 10.

When inserted into the mandrel 513, the open neck 102 of the preform 100 is pushed over the resilient plug 759 in the cylindrical seat 761 at the base of the mandrel. The plug 759 enters the open neck with an interference fit sufficient to support the weight of the preform 100 within the seat 761. The socket also serves to protect the neck 102 from overheating during the heating phase.

The body portion 103 of the preform 100 must be heated to the desired degree of plasticity so that the material in the body portion 100 of the preform can be biaxially oriented during the stretch-blow-molding process. However, neither the neck 102 nor the handle 113 should be subjected to the biaxial stretch blow molding process, and overheating must be avoided during the heating stage to prevent crystallization of the neck 102 and the handle 113, which results in a loss of strength. Thus, for transport through the heating stage, as shown in fig. 10, the handle 113 of the preform 100 is protected by the thermal insulation 519, while the neck 102 is protected by the cylindrical seat 761 of the mandrel 513.

As the preforms 100 are conveyed through the heating station 521, the preforms 100 are rotated on the mandrels 513 using a drive mechanism 522 to provide uniform heating of the body portions of the preforms while thermal shields 519 protect the handles from excessive heating.

As shown in fig. 11, the rotation of the mandrel is configured so that upon entering the stretch blow mold, the insulation and handle are properly oriented with the mold cavity. After the container is blow molded, the transport system removes the mandrel and container from the mold and the container is ejected from the mandrel.

Turning now to specific features of the handle 113 according to the present invention, the handle is injection moulded integrally with the body portion of the preform and comprises a ring portion or orientable material extending between upper and

lower attachment regions

115, 116 on the body portion 103 of the preform. The handle may be described as being made up of two main parts: a lower straight portion 118 sloping downward from the lower connecting area 116 and an arc portion 120 extending from an end 121 of the lower straight portion 118 to the upper connecting area 115.

The loop of orientable material forming the handle 113 has a generally uniform cross-section from adjacent the lower attachment area 116 to a progressively widening cross-section 124 proximate the upper attachment area 115, which reaches and maintains a maximum width adjacent the upper attachment area 115, as can be seen in figures 3 and 4. Fig. 5A to 5C show cross sections at typical regions of the handle 113. Fig. 5A at the lower straight section 118, fig. 5B at a greater length of the arcuate section 120, and fig. 5C at a wider cross-section near the upper connection region 115.

As can be seen in fig. 5A to 5C, the cross-section in each region of the loop or orientable material forming the handle 113 extends from the opposed

outer edges

130 and 131 towards the centre line 132, the thickness of the cross-section increasing from the

outer edges

130 and 131 towards the maximum thickness at the centre line 132.

Referring again to fig. 2, a first reinforcing element 135, a second reinforcing element 136 and a third reinforcing element 137, which are integrally formed, are provided at each of the upper connecting region 115, the lower connecting region 116 and a junction between the lower straight portion 118 and the arc portion 120 of the handle 113, respectively.

As shown in fig. 5C, the first stiffening element 135 at the upper attachment region 115 comprises a curved stiffening element having a width and cross-section that substantially corresponds to the width and cross-section of the widened portion 124 of the handle near the upper attachment region. The curved reinforcing element extends from a first separate attachment zone 140 on the body portion 103 of the preform (and on the blow-moulded container) below the upper attachment zone 115 and merges with a loop of orientable material adjacent the first end 141 of maximum width of the handle.

The second stiffening element 136 at the lower attachment area 116 of the handle comprises a rectilinear stiffening element having a width and cross section substantially corresponding to the width and cross section of the lower rectilinear portion 118. The rectilinear reinforcing element extends from the second single connection zone 142 above the lower connection zone 116 of the lower rectilinear portion of the handle, so as to merge with the lower rectilinear portion of the handle in the vicinity of the lower connection zone.

The third stiffening element 137 at the junction of the lower straight portion 118 and the curved portion 120 of the handle comprises another curved stiffening element having a width and cross-section that substantially corresponds to the width and cross-section of the handle at the junction of the lower straight portion 118 and the curved portion 120. The respective outer ends of the other curved element merge with each of the lower straight portion 118 and the arcuate portion 120.

It should be noted that the width of the first reinforcement element 135 is the same as the maximum width of the widened portion 124 of the handle in the vicinity of the upper connection region 115. This increased width of the first reinforcing element 135 provides a greater area to distribute the load of the container over the index finger of the hand (not shown) lifting the container shown in fig. 6, while the curvature of the first reinforcing element is selected to fit comfortably on the regular size index finger of a human hand.

Although not necessary, it is preferred that each reinforcing

element

135, 136 and 137 comprises a web of orientable material located within the limits formed between the main portion 112 and the first reinforcing element 135, between the main portion 112 and the second reinforcing element 136 and between the third reinforcing element 137 and the lower straight portion 118 and the curved portion 120, respectively, of the preform. Each web of orientable material is aligned with the centre line 132 of the handle and extends equally in both directions from the centre line 132.

In an alternative form of production apparatus, a rotatable mould may be provided on the turret means to receive a preform to be blown within the mould.

Claims

1. A method of handling a preform for stretch blow moulding a container having an integrally formed handle; the preform comprises a body portion and the integrally formed handle; the preform is transferred from a preform supply to a blow-moulding mould for blow-moulding the container; the method comprises the following steps:

-passing the preform through preform handle orientation means;

-transferring the preforms to a preform transport system;

wherein the handle comprises a loop of orientable material extending between upper and lower attachment areas located on the body portion of the preform; wherein the handle includes a straight line portion inclined downward from the lower connection region and an arc portion extending from one end of the straight line portion to the upper connection region; the handle has a generally uniform cross-section from near the lower attachment region to a gradually widening cross-section proximate the upper attachment region, the generally uniform cross-section reaching and maintaining a maximum width near the upper attachment region; the cross section extends from two opposite outer edges towards a center line, and the thickness of the cross section is gradually increased from the outer edges to the maximum thickness at the center line; the handle further comprises integrally formed first, second and third reinforcing elements at each of the upper and lower connection regions and at the junction between the linear and arcuate portions, respectively; the first reinforcing element at the upper attachment region comprises a first curved element having a width and cross-section substantially corresponding to a width and cross-section of the handle proximate the upper attachment region; the bending element of the first reinforcing element extends from a first separate attachment area on the body portion of the preform below the upper attachment area to merge with the handle near a first end of the handle having a maximum width; the second reinforcing element at the lower attachment region comprises a straight line element extending between the straight line portion of the handle and a separate attachment region on the main body portion of the preform above the lower attachment region of the handle; the third reinforcing element at the junction of the linear portion and the arcuate portion of the handle comprises another curved element extending between the linear portion and the arcuate portion of the handle; each of the first, second and third reinforcing elements having a width and cross-section substantially corresponding to a width and cross-section of adjacent linear and arcuate portions of the handle; each reinforcement element comprises a web of orientable material located within the limits formed between the main portion and the first reinforcement element, between the main portion and the second reinforcement element and between the third reinforcement element and the linear portion and the arcuate portion of the preform, respectively, each web of orientable material being aligned with the centre line and extending equally in both directions from the centre line.

2. A method of reducing the pressure on a supporting finger lifting a blow molded container using the preform of claim 1; the container is provided with an integrated handle; the method comprises the following steps:

-forming the handle with a straight portion and an arc-shaped portion, the straight portion being inclined downwards from the lower connection area and the arc-shaped portion extending from one end of the straight portion to the upper connection area;

-widening the cross-sectional profile of the arc-shaped portion in the vicinity of the upper connecting region to a maximum width of the handle, the cross-section of the handle extending from opposite outer edges of the handle towards a centre line, and the thickness of the cross-section increasing from the outer edges towards a maximum thickness at the centre line; and

-providing a first reinforcing element near the upper joining region, a second reinforcing element near the lower joining region, and a third reinforcing element at the junction between the linear portion and the arcuate portion; the first stiffening element comprises a first curved element having a width and cross-section substantially corresponding to a width and cross-section of the handle proximate the upper attachment region, the first curved element extending from a first separate attachment region below the upper attachment region to merge with the handle proximate the first end of the maximum width of the handle.

3. The method of claim 2, wherein the curvature of the stiffening element is selected to fit the normal size index finger of a human hand.

4. A blow molded container formed according to the method of any one of claims 1-3.

5. An injection molded preform having an integrally formed handle; the preform is formed in a first production step of stretch blow moulding a container; said container being blow molded from said preform including said handle as an integral ring of orientable material extending from an upper to a lower attachment area; the handle includes a linear lower portion and an arc portion extending from one end of the linear lower portion to the upper connection region; the gradually widening cross section of the handle of the preform from near the lower joining zone to near the upper joining zone has a substantially uniform cross section; the cross-section extends from two opposite outer edges of the handle towards a centre line, and the thickness of the cross-section gradually increases from the outer edges to the maximum thickness at the centre line; said cross-section reaching and maintaining a maximum width adjacent said upper connection region; the handle is further provided with a reinforcing element at the upper connection region; the reinforcing element comprises a curved element having a width and cross-section substantially corresponding to a width and cross-section of the handle proximate the upper attachment region; the bending element extends from a first separate attachment area below the upper attachment area to merge with the handle near a first end of the handle's greatest width.